Percussion fuze for shells



Oct. 22', 1968 K. MULLER PERCUSSION FUZE FOR SHELLS 2 Sheets-Sheet 1 Filed Oct. 17, 1966 Oct. 22, 1968 K. MULLER 3,406,630

PERCUSSION FUZE FOR SHELLS Filed Oct. 17, 1966 2 Sheets-Sheet 2 United States Patent 'PERCUSSION FUZE FOR SHELLS Kurt Miiller, Dielsdorf, Switzerland, assignor to Oerlikon- BuhrleHolding Ltd., Zurich, Switzerland Filed Oct. 17, 1966,'Ser. No. 587,220

. 14 Claims. (Cl. 102-73) ABSTRACT OF THE DISCLOSURE This invention relates to a percussion fuze for shells, in particular a percussion fuze with a fuze nose which has a cavity, in which a fusible body is arranged.

An object of the invention is to provide a fuze nose so that, on discharge of the shell, in front of the fusible body an air flow is'baffled, which heats up and thereby causes the fusible body to melt.

A main object of the invention is to shorten the melting time of the fusible body, in order to reduce the safe distance in front of the muzzle.

A further object of the invention is to improve the heat exchange between the air flow and the fusible body, while maintaining sufiicient mechanical strength of the same.

A further object of the invention is to direct the air flow past the fusible body in such a way that as far as possible it' flows over all sides of the latter.

With the above and other objects in view which will become apparent from the detailed description below, some preferred embodiments of the invention are shown in the drawings, in which:

FIGURE 1 is a partial perspective view shown diagrammatically of a fuze nose with parts in cross section of one modification.

- FIGURE 2 is a similar view of a modification.

FIGURE 3 is a perspective view of the fusible body used in FIGURE 1. e

FIGURE 4 is a perspective view of a modification of the fusible body.

FIGURE 5 is a similar view of a further embodiment of the fusible body.

FIGURE 6 is a similar view' of a still further embodiment. 7

FIGURE 7 is a similar view of still another embodiment of the fusible body.

FIGURE 8 is a diagrammatic perspective and crosssectional partial view of another modification of the invention.

FIGURE 9 is a similar view illustrating a still further embodiment. I

FIGURE 10 is a perspective view with parts in crosssection illustrating diagrammatically a still further embodiment of the invention.

FIGURE 11 is a top plan view of the form of the invention shown in FIGURE 1, and' FIGURE 12 is a partial longitudinal sectional view through the modification shown in FIGURE 2 wherein the fusible body as shown in FIGURE 7, is used.

In accordance with FIGURE 1, a disc-shaped light alloy extension 10 of a pin 11, e.g. of a firing pin, rests on a shoulder 13 of a casing component 14. A portion 16, opening up conically in an upward direction, forms the transition between this shoulder and the front face 18 of 3,406,630 Patented Oct. 22, 1968 ice the casing component 14. In this case, the height of this conical portion corresponds to the thickness of the extension 10. A fusible body 17, i.e. a body, preferably of a metal alloy, which melts at a low temperature, of which only a fragment is shown in FIG. 1, the design of which can however be seen from FIG. 3, rests on the extension 10, without touching the front surface 18, so that an annular space 26 remains between its outside surface 24 and the inside wall 25 of the fuze nose 19, which is described in greater detail in the following.

The fuze nose 19, clinched over the front end of the casing component 14, is securely screwed to the casing component 14, in a way not shown. This fuze nose 19 has a central hole 20, which is bounded by a flange 21, flat in front, arranged at right angles to the fuze axis. The fusible body 17, resting on the firing pin extension 10, abuts against the inside surface 22 of the flange 21 and prevents the firing pin extension 10 from sliding forward, as long as the fusible body has not melted. In the fuze nose 19, four slots 28, serving as air passages, are provided equally spaced around the circumference, which penetrate the flange 21 and extend through the fuze nose wall to behind the fusible body 17.

As shown in FIGURE 3, four radially arranged grooves 23 of rectangular cross section, which extend over the whole width of the ring-shaped fusible body 17, are provided on the under side, viewed in the direction of flight, of the fusible body. The grooves 23 are offset in relation to the slots 28 in the fuze nose 19 by 45, as can be seen from FIGS. 1 and 11.

The mode of operation of the fuze nose described is as follows: On discharge of a spun shell fitted with the latter, the air bafiled in the hole 20 is compressed and heated. It flows in part over the front surface of the fusible body 17 into the slots 28 and in part through the grooves 23 in the cavity 26, and from here also into the slots 28. The off-setting mentioned of the grooves in relation to the slots 28 results in a flow of the air in this space along the outside surface of the fusible body 17, which promotes even heating of the latter. After a very short time, e.g., after the shell is about 20 m. from the muzzle, the body melts, whereupon the melted metal is spun off. The extension 10 is now released and can be slid forward to arm the fuze. On impact of the fuze on the target, the edge of the extension 10 is sheared off on the shoulder 13 and the pin 11 is slid to the rear.

The fuze nose described can, for example, be used with a percussion fuze, as described in U.S. Patent No. 3,007,412.

The fuze nose 19 according to FIG. 2 has, instead of the slots 28 of FIG. 1, holes 30 evenly distributed around the circumference below the flange 21, which completely penetrate the wall of the fuze nose 19. The latter is, in a similar way to that described in connection with FIG. 1, screwed to a casing component 14, which is provided with a shoulder 13 serving as a support for the extension 10. From the latter, a conical portion 16 leads to the front face 18 of the casing component 14. A ringshaped fusible body 17', as in FIGURE 4, rests on the disc 10 and is pressed against this disc by the flange 21 abutting against its front face. Compared to the version as in FIGURE 1, the fuze nose as in FIGURE 2 has the advantage that it is less weakened by the holes 20 than by the slots 28.

According to FIGURE 4, radially arranged grooves 23, of rectangular cross section, are provided on both the rear and the front side of the fusible body 17, whereby the groove 23 on one side are offset in relation to the grooves 23 on the other side of the fusible body 17. The fusible body can be so set in the fuze nose that each of the grooves 23 is in line with one of the holes 30.

The mode of operation of the fuze nose as in FIG- URE 2 is essentially the same as that described for FIG URE 1. There is a difference insofar as the whole amount of air impinging on the fuze nose must first of all reach the annulus 26, in order to flow out from here through the holes 30.

The fusible bodies as in FIGURES 3 and 4 could also be interchanged in the fun noses as in FIGURES 1 and 2. In each of these two fuze noses, a fusible body 17" as shown in FIG. 5 can, moreover, be used. This fusible body has radially arranged holes 31, the axes of which lie on the central plane of the body. On account of the large number of holes 31, it can be inserted in any way desired in the fuze nose, without the alignment of the individual holes 31 with the holes 30 of FIGURE 2, or the slots 28 of FIGURE 1, needing to be observed.

Two further versions of fusible bodies, with which each of the two fuze noses as in FIGURES 1 and 2 can be assembled, are shown in FIGURES 6 and 7 at 17a and 17b. In FIGURE 12 is shown the fuze nose as in FIG- URE 2 in longitudinal section and the fusible body 17b, as in FIGURE 7, installed in it. The fusible body 17a as in FIGURE 6 would, however, fit int-o this fuze nose in exactly the same way.

As in FIGURE 6, the ring-shaped fusible body 17a has on its outer surface 24 recesses 32 directed radially outwards. The base surfaces 33 of these recesses lie on a cylindrical surface, the diameter of which is less than the diameter of the central hole 20 in the fuze nose 19.

In FIGURE 7, the base surface 33 of the recesses 32 in the fusible body 17 are inclined in relation to the fuze axis. This design of the fusible body 17b is specially suited to the fuze nose 19, provided with holes 30, shown in FIGURE 2. With this design of the fusible body, good guidance of the air as regards flow technique is attained, and thereby better heat exchange.

The mode of operation of the fuze nose as in FIG- URE 12, with a fusible body as in FIGURES 6 or 7, is that the air entering the hole 20 flows through the recesses 33 in the annulus 26 and from here through the holes 30 into the open. This air heats the ribs 24 between the recesses 33 and melts them away. As a result, the fusible body 17 loses its hold on the flange 21 and makes possible forward sliding of the disc 10. As can be understood without more discussion, the example as in FIG- URE 12 also permits the use-of disc-shaped fusible bodies, as through passage of air only takes place at the edge. In the case of the example as in FIGURE 8, the disc rests on a shoulder 13 on the casing component 14, in the same way as shown in FIGURES 1 and 2. The front end face of the disc 10 is approximately flush with the front face 18 of the casing component 14. On the front face of the disc 10, along its edge, a ring of projections 29 of equal height is provided, between which are located radial grooves 34. The projections 29 form a common front surface, on which rests the ring-shaped fusible body 170, made without grooves or holes, of rectangular cross section. This, for its part, is held up by the flange 21 of the fuze nose as in FIGURES 1 or 2, not shown in FIGURE 8, which rests on the front face of the fusible body. The mode of operation of this fuze nose is essentially the same as described for FIGURES 1 and 2. The air, baflied on the disc 10, passes through the grooves 24 in the annulus between the casing component 14 and the fuze nose and flows through the slots 28 (FIGURE 1) or the holes 30 (FIGURE 2) into the open. Thereby it flows in contact with the fusible body along its inner edge and along the grooves 34, whereby the fusible body is caused to melt.

In FIGURE 9, the disc-shaped extension 10 is provided with a cylindrical portion 38 in its middle, which rises above the front end face of the disc 10, and the diameter of which coincides with the inside diameter of the fusible body 17:] has four radial grooves 23 formed on its upper end face and, symmetrically offset to these, four grooves 37, likewise radial, arranged on its lower end face. In addition, at the sites of these grooves 37, axially aligned recesses 36 are arranged in the inside surface 35 of the fusible body 17d, which form a connection between the grooves 37 and the upper end face of the fusible body. The disc 10 with the cylinder 38 can be installed equally wellin the fuze noseas in FIG- URE 1 and a's in FIGURE 2, whereby the disc comes to rest on the shoulder 13 in the way shown in these figures. The mode of operation is essentially the same as that described.

There is a difference in that between the inside edge of the flange 21 and the cylinder 38 an annular clearance is formed, through which the air is directly compressed against the front end face of the fusible body 17d. Hereby the sensitivity on target of the fuze can be increased.

FIGURE 10 shows a version of the fuze nose 19,"in which a cylindrical portion of the inside wall 25 joins on to the flange 21, which cylindrical portion is terminated by a drilled through intermediate bottom 39. In the latter, the pin 11 carrying a shearing plate 40 and the disc 10 is slidably guided. From the front face of the fuze nose 19 inwards, four axially-running slots 28 are formed in the wall, which extend down to the level of thedisc 10. The fusible body 17, held between the flange 21 and the disc 10, rests all around against the inside wall 25, and is provided on its lower end face with four radial grooves 23, as shown in FIGURE 3. As FIGURE 10 shows, the fusible body is so inserted in the fuze nose that the grooves 23 open into the slots 28.

The mode of operation of the fuze nose in FIGURE 10 is that the air flowing on to it on discharge of the shell is baflied on the fusible body 17 and on the extension 10. It flows away on the one side directly through the slots 28 and on the other side it passes through the grooves 23 and the slots 28, to the outside of the fuze nose. As a result of the heating of the fusible body 17 thereby taking place, the latter melts and hence liberates the extension 10. It is slid forward, together with the pin 11, through a self-aligning rotor, or through the self-destruction device of the fuze, as described in US. Patent No. 3,007,412. On impact of the shell on the target, the extension 10 and the pin 11 are slid to the rear, whereby the disc 40 is sheared off.

What is claimed is:

1. Percussion fuze for shells, comprising an axially slidable pin, a fuze nose having a cavity open to the front into which said pin extends, a fusible body in said cavity preventing said pin from sliding forwardly, said fusible body having an end face exposed to the air flow on discharge of the shell, said air flow being baffled in said cavity in front of said fusible body, at least one air passage arranged partly in said fusible body and partly in said fuze nose for leading away the air flow from said fusible body, said fusible body having an outside generated surface area, with at least one recess facing radially outwards on said generated surface area, said recess forming a part of the portion of said air passage, and the base surface of said recess being inclined to the axis of the fuze.

2. Percussion fuze for shells, comprisingan axially slidable pin, a fuze nose having a cavity open to the front into which said pin extends and an inside bearing surface facing to the rear, a disc-shaped extension in said cavity on said pin, an annular shaped fusible body in said cavity having two opposite end faces, one of said end faces resting on said disc-shaped extension and the other end face being supported on said bearing surface, a casing component to which said fuze nose is secured on which said disc-shaped extension rests, at least one air passage arranged partly in said fusible body and partly in said fuze nose, for leading away the air flow from said fusible body and radially arranged grooves provided on said disc-shaped extension on the side of said extension adjacent to said fusible body.

3. Percussion fuze for shells,

comprising an axially slidable pin,

a fuze nose having a cavity open to the front into which said pin extends and an inside bearing surface facing to the rear, a disc-shaped extension in said cavity on said pin, an annular shaped fusible body in said cavity having two opposite end faces, one of said end faces resting on said disc-shaped extension and the other end face being supported on said bearing surface, a casing component to which said fuze nose is secured on which said disc-shaped extension rests, at least one air passage arranged partly in said fusible body and partly in said fuze nose, for leading away the air flow from said fusible body, said fuze nose having slots which extend into said cavity to the underside of said fusible body forming a part of the portion of said air passage located in said fuze nose, and rear grooves are provided in said fusible body arranged offset in relation to said slots forming a part of the portion of said air passage located in said fusible body.

4. Percussion fuze "for'shells, comprising an axially slidable pin, a fuze nose having a cavity open to the front into which said pin extends and an inside bearing surface facing to the rear, a disc-shaped extension in said cavity on said pin, a fusible body in said cavity having two opposite end faces, one of said end faces resting on said disc-shaped extension and the other end face being supported on said bearing surface, a casing component to which said fuze nose is secured on which said disc-shaped extension rests, at least one air passage arranged partly in said fusible body and partly in said fuze nose, for leading away the air flow from said fusible body, said fuze nose having slots which extend into said cavity to the underside of said fusible body forming a part of the portion of said air passage located in said fuze nose, and front grooves are provided in said fusible body arranged offset in relation to said slots forming a part of the portion of said air passage.

5. Percussion fuze for shells, comprising an axially slidable pin, a fuze nose having a cavity open to the front into which said pin extends, a fusible body in said cavity preventing said pin from sliding forwardly, said fusible body having an end face exposed to the air flow on discharge of the shell, said air flow being baffled in said cavity in front of said fusible body, at least one air passage arranged partly in said fusible body and partly in said fuze nose for leading away the air flow from said fusible body, said fusible body having a central hole forming part of the portion of the air passage located in said fusible body, said fusible body having a front and a rear end face with radially arranged grooves on both end faces forming a part of said air passage located in said fusible body, and said front grooves are off-set with relation to said rear grooves of said fusible body.

6. Impact igniter for a projectile comprising a casing having an ignition nose with an impact face symmetrical with the longitudinal axis of said casing, a stop face on said nose, said casing having a lateral casing wall and a first hollow space open towards the front and extending along said axis, a first group of air passages in said casing wall, an annular fuze body located in said hollow space having a front and a rear surface, said front surface abutting said stop face and said rear surface having radial recesses extending over the entire breadth of said rear surface, a disc support located in said hollow space abutting said rear surface, said disc support being displaceable towards the front in said hollow space upon melting of said fuze body, said disc support together with said recesses defining a second group of air passages, a second hollow space defined by said wall of the casing and said fuze body into which said first group of air passages opens, said second hollow space being connected with said first mentioned hollow space via said second group of air passages, and recesses in one of said two surfaces defined by said stop face and said front surface defining a third group of air passages connecting said hollow spaces.

7. Impact igniter for a projectile with an axially displaceable firing pin comprising an ignition nose having an air cavity open towards the front into which said firing pin extends, an annular fuze body in said nose preventing a displacement of said firing pin towards the front, said fuze body having a front and a rear annular surface with an interior and an exterior edge, said rear surface opposite to the direction of flight having recesses extending radially from said interior towards said exterior edge of said surface, a first air conduit defined partially by said front surface of said fuze body, a second air conduit defined partially by said recesses and said two air conduits opening into said air cavity, and a third air conduit connected to said first and second air conduits so that air accumulating in said cavity flows through said air conduits and passes along both surfaces of said fuze body.

8. Impact igniter as claimed in claim 7 wherein recesses are provided in said ignition nose to form said third conduit and an annular conduit is provided between said fuze body and said ignition nose forming a connection from one of said first mentioned air conduits with said third conduit.

9. Impact igniter as claimed in claim 7 wherein slots are arranged in said ignition nose which define said third air conduit and said recesses of said fuze body are staggered with respect to said slots.

10. Impact igniter as claimed in claim 7 wherein radial recesses are provided extending over the entire breadth of said front surface, said recesses defining said first air conduit, and slots are arranged in said ignition nose defining said third air conduit, said recesses of said fuze body being staggered with respect to said slots.

11. Impact igniter as claimed in claim 10 wherein said recesses on said front surface are staggered with respect to said recesses on said rear surface.

12. Impact igniter as claimed in claim 9 wherein an annular conduit is provided between said ignition nose and said fuze body forming a connection between said recesses of said fuze body and said slots.

13. Impact igniter as claimed in claim 7 wherein bores are arranged radially in said ignition nose which define said third air conduit and said recesses of said fuze body are staggered with respect to said radial bores.

14. Impact igniter as claimed in claim 7 wherein a cylindrical part is provided on said firing pin which penetrates said fuze body and axial grooves are provided in the surface of said fuze body abutting said cylindrical part defining said second air conduit.

References Cited UNITED STATES PATENTS 2,137,983 11/1938 Remondy 102-77 2,270,342 1/1942 Remondy 10273 2,367,245 1/ 1945 Thibodeau 102--76 3,007,412 11/1961 Kipfer 102-81 X 2,766,964 10/ 1956 Almquist et al 10270.2 3,093,076 6/1963 Blomgren l0270.2

BENJAMIN A. BORCHELT, Primary Examiner.

G. H. GLANZMAN, Assistant Examiner. 

